1. Field of the Invention
This invention relates to a process for the low polymerization of isobutene using a solid acid catalyst, in particular, high silica mordenite catalyst with a specified solid acid quantity, and more particularly, it is concerned with a process for the selective low polymerization of only isobutene in an isobutene-containing hydrocarbon mixture.
2. Description of the Prior Art
In the low polymerization of isobutene in a hydrocarbon mixture containing isobutene, it is well known to contact the hydrocarbon mixture with a solid acid catalyst such as silica.alumina, zeolite or cation exchange resin. This method is used for the removal of isobutene in C.sub. 4 hydrocarbon mixtures.
For example, there have hitherto been proposed (1) a method comprising contacting a C.sub. 4 hydrocarbon mixture with an isomerization catalyst such as palladium, platinum or nickel to isomerize 1-butene in 2-butene, further contacting with a solid acid catalyst such as activated clay or silica.alumina to low-polymerize isobutene and separating the resulting low polymers (Japanese Patent Application OPI (Kokai) No. 8201/1976), (2) a method comprising contacting a C.sub. 4 hydrocarbon mixture with a crystalline molecular sieve (10X Molecular Sieve) having effective pores of about 8 to 8.2.ANG. to remove isobutene (Japanese Patent Publication No. 42803/1972), (3) a method comprising contacting a C.sub. 4 hydrocarbon mixture with a synthetic zeolite (ZSM-4) to low-polymerize selectively isobutene (Japanese Patent Publication No. 29121/1976) and (4) a method comprising feeding a C.sub.4 hydrocarbon mixture to a distilling column packed with a cation exchange resin, lowpolymerizing isobutene and separating and removing the low polymers from the bottom thereof (U.S. Pat. No. 4,215,011).
However, any of these methods is not suitable as a method of producing 1-butene free from isobutene since 1-butene contained in the C.sub.4 hydrocarbon mixture tends to be isomerized in 2-butene.